Method for establishment of connections of pre-determined performance for a packet-oriented communication network with a resource manager

ABSTRACT

Transmission resources are controlled in individual transmission paths in a packet-oriented communication network, whereby data-packet address information which identifies the origin and the goal of the data packets, is transmitted to a resource manager, responsible for a transmission path, from a network transmission device. On a resource request, for a connection to be subsequently generated, the origin and goal thereof are compared with the origin and goal of the previously transmitted data packets by the resource manager. Should there be agreement, the resource manager can deduce that the connection to be established can equally run over the corresponding transmission path. Correspondingly, establishment of further connections occurs, depending upon the available resources of the transmission path.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and hereby claims priority to PCTApplication No. PCT/DE01/03325 filed on 29 Aug. 2001 and GermanApplication No. 100 45 205.1 filed on 13 Sep. 2000, the contents ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

In many packet-oriented communication networks, such as the Internet, noperformance is guaranteed for connections between terminals in thesecommunication networks if no additional precautions are taken. Theperformance of a connection is also frequently known as “Quality ofService” (QoS) and can include different transmission and connectionresources, such as the transmission bandwidth, the transmission rate,the permissible error rate and/or the transmission duration.

In up-to-date communication systems, which are frequently based on suchpacket-oriented communication networks, resource managers are providedin order to ensure a predetermined performance. In each case these areassigned to a communication network or subnetwork in order to manage itstransmission resources. When there is a resource manager, transmissionresources which can be predetermined specifically for connections can bereserved for the connections which have to be established. Following asuccessful reservation of transmission resources, the resource managermonitors the continuous availability of the reserved transmissionresources for the connection concerned.

Usually when a connection needs to be established, its origin anddestination are transmitted to a resource manager so that it can reservethe necessary transmission resources. The resource manager then uses thetransmitted origin and destination information to determine the pathover which the connection needing to be established will run. To do thisaccording to known related art, the resource manager needs preciseinformation about the complete topology of the communication network.This information is transmitted to the resource manager very expensivelywith the aid of a routing protocol. A method of this kind is describedin the document “Performance of QoS Agents for Provisioning NetworkResources” by Schelén et al. in the Proceedings of IFIP SeventhInternational Workshop on Quality of Service (IWQoS'99), London, June1999.

In many cases connections need to be established between differentsubnetworks in a communication system, for which purpose the subnetworksthemselves may well have a very large transmission bandwidth, but arecoupled over a transmission path with a proportionately narrowtransmission bandwidth. A typical example of this is when local areanetworks (LANs) are coupled over a public telephone network. In thiscase the telephone network with its proportionately narrow transmissionbandwidth represents a bottleneck for data needing to be exchangedbetween the local area networks. This leads to the problem of how tocontrol transmission resources efficiently even for connections runningthrough such bottlenecks.

SUMMARY OF THE INVENTION

One possible object of the present invention is to specify a method fora packet-oriented communication network, for the purpose of establishingconnections of predetermined performance, a method which enablestransmission resources for connections running over individualtransmission paths, in particular individual transmission bottlenecks,to be efficiently controlled at low cost.

Within the scope of the method, a transmission resource in atransmission path is managed by a resource manager. A networktransmission device which transmits data packets over the transmissionpath transmits to this resource manager data packet address informationidentifying the origin and destination of the data packets. The resourcemanager thus has the information that data packets with thecorresponding origin and destination will be transmitted over thetransmission path concerned. On a subsequent resource request for aconnection to be established, if the origin and destination thereofmatch the origin and destination of the previously transmitted datapackets, the resource manager can then deduce that the connection to beestablished will—at least with a very high probability—likewise berouted over the corresponding transmission path. Correspondingly,further connections are established, depending upon the availableresources of the transmission path.

An advantage of this method relates to the packet address information,in which current information on the path of data packets or connectionsis transmitted to the resource manager, in which an information databaseis then automatically updated via the connection routing management inthe communication network. This is particularly advantageous in thosecommunication networks where the routing management of a path orconnection between predetermined terminals changes frequently.

With regard to the method, let it be understood that a connection alsoincludes subelements known as virtual connections, connection linegroups, connection paths or general data streams, with a defined originand destination in each case. In this sense devices such as terminals,network nodes, switching equipment, communication networks, partialnetworks or subnetworks can be considered as the origin and destinationof such connections.

The performance of a connection under the control of the resourcemanager can involve quite different transmission resources, such astransmission bandwidth, transmission rate, permissible error rate,transmission delay and/or any other Quality-of-Service parameters, asthese are known, and may if necessary be specific to particular serviceclasses or priority classes.

Link information can advantageously be transmitted to the resourcemanager with the data packet address information, enabling the resourcemanager to identify the transmission path concerned. Typical linkinformation includes data identifying the network transmission deviceand if necessary data identifying one of the multiplicity oftransmission paths connected thereto. By the transmission of linkinformation, the resource manager is put in a position to exerciseseparate control over a multiplicity of transmission paths, each ofwhich is identifiable with the aid of the link information, by themethod to which aspects of the invention relate.

In an advantageous development the network transmission device can—ifnecessary at regular intervals—transmit information to the resourcemanager about the available set of resources on the transmission path.In this way the extent of the resources being managed by the resourcemanager can be updated on the basis of the latest transmissionsituation. This is particularly advantageous in that it directlynotifies the resource manager about unforeseen adverse effects on thebehavior of the transmission path, without needing to make a detourthrough a costly routing protocol.

In addition various measures can be taken to reduce the amount of datato be transmitted from the network transmission nodes to the resourcemanager:

For example, before transmitting data packet address information a checkis first made on whether data packet address information with the samecontents has already been sent earlier. Transmission then takes placeonly if the check turns out to be negative. In order for the check to bepossible, previously sent items of data packet address information mustbe stored by the network transmission device.

Furthermore, depending on the data packet address information, thenetwork transmission device can send the resource manager routinginformation for recognizing connections running over the transmissionpath. Such routing information can typically be determined by accessinga routing table. In this instance routing information can mean, forexample, that all data packets with an origin and/or destinationsubnetwork address specified in the routing information will betransmitted over the transmission path.

In addition the data packet address information in a data packet can betransmitted dependent on transmission information contained in that datapacket. By this it is possible for instance for data packets that areexchanged between non-connectable terminals or applications on thecommunication network to be excluded from using the method. Such packetscan be recognized by the network transmission nodes by transmissioninformation contained in the data packet, such as an origin addressand/or destination address, or in certain cases a protocol number and/orport number.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention willbecome more apparent and more readily appreciated from the followingdescription of the preferred embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 shows a communication system with two subnetworks connected overa transmission path in the course of transmitting data packets; and

FIG. 2 shows the same communication system in the course of establishinga connection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout.

FIG. 1 and FIG. 2 show in each case diagrams of the same communicationsystem with two packet-oriented, preferably Internet protocol basedcommunication subnetworks LAN1 and LAN2, which in this exemplaryembodiment take the form of local area networks. Local area network LAN1has a router device R1 which is connected over a transmission path US toa router device R2 on local area network LAN2. For the exemplaryembodiment it can be assumed that the transmission path US hassignificantly fewer transmission resources than the local area networksLAN1 and LAN2 and therefore represents a transmission bottleneck for adata exchange between local area networks LAN1 and LAN2. A situation ofthis kind frequently occurs in practice, for instance when amultiplicity of local area networks belonging to a company are locatedin different places and connected over the public communication networkor the Internet. Local area networks connected together in this way arealso frequently known as a “virtual private network” (VPN).

Instead of the router devices R1 and R2, which here take the form ofdevices known as edge routers, it is also possible to connect togetherthe local area networks LAN1 and LAN2 with the aid of elements known asgateways, switching devices, modems or general network nodes or networktransmission nodes belonging to a private or public communicationnetwork.

To manage the transmission resources of the local area networks LAN1 andLAN2 and in particular the transmission path US, a central resourcemanager RM is arranged within the communication system. The resourcemanager RM is the element in the communication system that isresponsible for reserving transmission resources for connections whichneed to be established, and for ensuring the performance of establishedconnections. Transmission resources or performance can involve quitedifferent transmission parameters, such as a maximum or mediumtransmission bandwidth, transmission delay and/or transmission errorrate. For all connections which require a performance guarantee in thecommunication system, the corresponding transmission resources must berequested from the resource manager RM and released again once theconnection is cleared.

In addition a terminal EG1 is connected to local area network LAN1 and aterminal EG2 is connected to local area network LAN2. Terminals EG1 andEG2 can take the form of any terminal for the communication of speech,video and/or data, or can even be a personal computer. Addressinformation A1 is assigned to terminal EG1 and address information A2 isassigned to terminal EG2. Terminals EG1 and EG2 can be uniquelyaddressed and identified in the communication system by addressinformation A1 and A2. In an alternative embodiment it is possible toprovide another router device or switching device or anothercommunication system network node in place of at least one of theterminals EG1 and EG2.

Furthermore the communication system has a central device known as agatekeeper GK which is connected to the resource manager RM. Thegatekeeper GK is responsible for logical control, that is, theestablishment, clearing down and monitoring of connections in thecommunication system. To establish a connection with guaranteedperformance, the origin and destination of the connection to beestablished must be sent to the gatekeeper GK together with a resourcerequest. In the exemplary embodiment the gatekeeper GK satisfies ITU-Tstandard H.323.

According to another embodiment a device known as an SIP server, whichsupports the protocol known as SIP (session initiation protocol) inaccordance with the IETF standard, can be used instead of the gatekeeperGK.

The resource manager RM moreover has an allocation table TAB where theorigin and destination addresses of data transfers in the communicationsystem are assigned to individual transmission paths.

FIG. 1 shows the communication system in the course of transmitting datapackets DP1 and DP2 over transmission path US. In the exemplaryembodiment, data packets DP1 are transmitted into local area networkLAN1 by terminal EG1, in the scope of a data transfer which is notfurther defined, with address information A1 as the origin address andaddress information A2 identifying terminal EG2 as the destinationaddress. The router device R1 of local area network LAN1 recognizes bythe destination address A2 that the destination terminal EG2 isaccessible over local area network LAN2 and consequently transmits datapackets DP1 over the transmission path US and the router device R2 intolocal area network LAN2. This then forwards data packets DP1 to thedestination terminal EG2. In a similar way data packets DP2 aretransmitted into local area network LAN2 by terminal EG2, in the scopeof another data transfer which is not further defined, with addressinformation A2 as the origin address and address information A1identifying terminal EG1 as the destination address, and are transmittedfrom there over local area network LAN1 to destination terminal EG1.

In the exemplary embodiment, both the data transfer from terminal EG1 toterminal EG2 and the data transfer in the opposite direction are carriedout over the transmission path US. In general, however, the path takenby data transfers can also be dependent on the direction of transfer.Furthermore the transmission resources of the transmission path US canbe different for the two directions of transmission, and accordingly theresource manager RM generally manages them separately.

The router device R1 transmits the origin address contained in the datapacket DP1 which is to be transmitted, in this example A1, and thedestination address, in this example A2, together with link informationLUS identifying the transmission path US, to the resource manager RM.The resource manager then stores the address information A1 as theorigin address, the address information A2 as the destination address,and the link information LUS, cross-allocated, in the allocation tableTAB. In a similar way the router device R2 transmits the origin addresscontained in the data packets DP2 which is to be transmitted, in thisexample A2, and the destination address, in this example A1, togetherwith link information LUS identifying the transmission path US, to theresource manager RM. The resource manager stores the address informationA2 as the origin address, the address information A1 as the destinationaddress, and the link information LUS, cross-allocated, in theallocation table TAB. The resource manager RM can therefore determine byaccessing the allocation table TAB that both a data transfer fromterminal EG1 to terminal EG2 and a data transfer in the oppositedirection are each being carried out over transmission path US. Readingand transmitting the address information A1 or A2 contained in the datapackets DP1 or DP2 can be carried out by the router devices R1 and R2preferably with the aid of an element which additionally has to beimplemented, known as a monitoring component, for observing data packettraffic. The transmission of information from the router devices R1 andR2 to the resource manager RM preferably takes place over logicalsignaling channels.

Preferably the router devices R1 and R2 only ever transmit addressinformation and link information to the resource manager RM when theinformation concerned changes. For this purpose address information tobe transmitted from the router devices R1 and R2 to the resource managerRM is stored and compared with the current address information containedin subsequent data packets. The current address information is onlytransmitted to the resource manager RM if it does not match the storedaddress information. This prevents identical address and linkinformation for each of the individual data packets DP1 or DP2 beingrepeatedly transmitted to the resource manager RM.

The amount of information to be transmitted from the router devices R1and R2 to the resource manager RM can also be reduced by sending theresource manager generalized routing or address information, forinstance in the form of subnetwork addresses. The router devices R1 andR2 can frequently recognize with the aid of a data packet that has to besent over the transmission path US, that yet more data traffic will becarried over the transmission path US. In this case the router deviceR1, for example, by accessing a routing table which states that all datapackets directed to the local area network LAN2 are to be transmittedover the transmission path US, can determine with the aid of a datapacket arriving from terminal EG1 that all data packets from terminalEG1 which are to be transmitted into local area network LAN2, regardlessof the destination terminal, will be sent over the transmission path US.In this case the router device R1 can send the resource manager RM theaddress information A1 as the origin address and the subnetwork addressof the local area network LAN2 as the destination address.

FIG. 2 shows a diagram of the communication system establishing aconnection from terminal EG1 to terminal EG2. The connection to beestablished is independent of the preceding data transfers between theterminals EG1 and EG2. A situation of this kind frequently occurs when,for example, terminals EG1 and EG2 are in the form of personal computersbetween which both an active transfer of files takes place without aperformance guarantee and connections for transmitting voice overInternet protocol (VoIP) are established with guaranteed performance.

Within the scope of establishing a connection, connection signaling VASis carried out between the terminal EG1 and the gatekeeper GK as well asbetween the gatekeeper GK and the terminal EG2. For this purpose logicalsignaling channels are provided between the terminal EG1 and thegatekeeper GK as well as between the gatekeeper GK and the terminal EG2.The logical signaling channels for connection establishment signalingare shown in FIG. 2 by unbroken double-headed arrows. Connectionestablishment signaling is preferably carried out in accordance withITU-T Recommendation H.323v2. This type of connection establishmentsignaling is also frequently known as “fast connect”.

Within the scope of connection establishment signaling VAS, the addressinformation A1 identifying the connection origin EG1, the addressinformation A2 identifying the connection destination EG2 and a resourcerequest RA are transmitted to the gatekeeper GK by the terminal EG1initiating the connection. The gatekeeper transmits the resource requestRA and the address information A1 and A2 to the resource manager RM andinitiates the connection between the terminals EG1 and EG2.

According to an alternative embodiment of the connection establishment,the terminal EG1 can transmit to the gatekeeper GK a logical destinationaddress (not shown) which identifies the connection destination EG2,such as an alias address, e-mail address, URL (uniform resource locator)or E.164 address. The logical destination address is then converted bythe gatekeeper GK into a transport address identifying the connectiondestination EG2, in this example A2, and transmitted in this form to theresource manager RM. The transport address in this case refers to theaddress information by which the data packets can be steered through thecommunication system. A transport address of this kind can, forinstance, be composed of an IP address (IP: Internet protocol) and aport number.

When the address information A1 and A2 is transmitted, the origin anddestination of the connection that needs to be established is known tothe resource manager RM, but not its path.

In order to obtain information on the path of the connection that needsto be established, the resource manager RM looks in the allocation tableTAB for an entry with an origin address that matches the addressinformation A1 transmitted by the gatekeeper GK and a destinationaddress that matches the address information A2 transmitted by thegatekeeper GK. If a subnetwork address is contained in the allocationtable TAB as the origin address or destination address, a match betweenthis subnetwork address and the corresponding subnetwork address part ofthe address information A1 or A2 concerned transmitted by the gatekeeperGK is judged to be a match within the meaning of the method.

In the exemplary embodiment the very first entry in the table is foundto be in agreement and the link information LUG for this entry is read.By the link information LUG read in this way, the resource manager RMrecognizes that the connection which needs to be established will berouted over the transmission path US identified by the link informationLUG. This causes the resource manager RM to take into consideration inparticular the currently available transmission resources of theidentified transmission path US when making transmission resourcesavailable in accordance with the resource request RA.

If the requested transmission resources on the transmission path US arenot currently available, establishment of the connection is cancelled.In the event that no entry showing agreement in the above sense is foundin the allocation table TAB, the connection establishment may preferablybe continued, although the resource manager RM does not know that theconnection is routed over the transmission path US. This method can insome cases lead to a situation where the requested transmissionresources can no longer be guaranteed after the connection isestablished. Such cases are very rare however, since in the main theycan occur only during a short starting phase of the communication systemwhen terminals EG1 and EG2 have not yet exchanged any data packets. Evenso, in order to avoid such cases, reserves of resources can be providedby the resource manager RM.

Once the connection is established, useful data DATA can be exchangedbetween terminals EG1 and EG2 over the local area networks LAN1 and LAN2and the transmission path US with guaranteed performance.

As already mentioned above, the transmission resources available on thetransmission path US are considerably less than the transmissionresources of the local area networks LAN1 and LAN2. For this reason thetransmission resources available on the transmission path US are thecritical factor for the control of the transmission resources for theconnection. The special control of the transmission resources on thetransmission path US by the resource manager RM is indicated in FIG. 2by a dotted arrow.

The transmission resources on the transmission path US can if necessarybe managed and controlled by service class, priority class and/ortransmission direction. A simple implementation of such a resourcemanagement includes dividing the data traffic into different serviceand/or priority classes and assigning to each of these classes aproportion of the available transmission resources of transmission pathUS—if necessary making them specific to the direction of transmission.These kinds of data traffic classes are also frequently referred to asDiffServ classes. Preferably a class of data traffic for connectionlessdata traffic, i.e. traffic for which no logging on is required, can alsobe provided. Data traffic belonging to this class of traffic would haveno performance guarantee. To manage traffic classes the resource managerRM can be provided with a resource table (not shown), with entries foreach individual traffic class showing the transmission resourcesreserved for connections and the resources still remaining.

So that data packets that have to be transmitted can be allocated toindividual traffic classes with guaranteed performance, these datapackets can be labeled with traffic class information. From thislabeling the router devices R1 and R2 can recognize the traffic class towhich a data packet due for transmission is assigned, and whichtransmission resources are reserved for this data packet if appropriate.

It is furthermore possible to provide for the resource manager RM tonotify the router device R1 or R2 about every successful resourcereservation affecting the transmission path US. The router device R1 orR2 can then be operated in such a way that only data packets fromconnections for which the resource reservation has been notified in thisway will be handled in accordance with the resource reservation andtraffic class association concerned.

The invention has been described in detail with particular reference topreferred embodiments thereof and examples, but it will be understoodthat variations and modifications can be effected within the spirit andscope of the invention.

1. A method for establishing a packet-oriented connection ofpredetermined performance using a network transmission device and atransmission path, comprising: managing a transmission-oriented set ofresources on the transmission path by a resource manager, reading datapacket address information from data packets that have been transmittedor are to be transmitted over the transmission path, the data packetsbeing independent from the connection to be established, the addressinformation identifying the origin and destination of the data packetsand being read by the network transmission device; transmitting theaddress information from the network transmission device to the resourcemanager, transmitting a resource request to the recourse manager inorder to establish the connection, the resource request havingconnection information identifying the origin and destination of theconnection, the address information being transmitted before theresource request, using the connection information and the data packetaddress information to determine whether the origin and destination ofthe connection match the origin and destination of the data packets, andif the origin and destination of the connection match the origin anddestination of the data packets, considering available resources on thetransmission path in further evaluating establishment of the connectionsuch that a positive match causes the available resources to beconsidered.
 2. The method according to claim 1, wherein link informationidentifying the transmission path is transmitted to the resource managerwith the data packet address information.
 3. The method according toclaim 1, wherein the connection is established only if the resourcerequest does not exceed available resources on the transmission path. 4.The method according to claim 1, wherein the network transmission devicetransmits resource information to the resource manager concerningavailable resources on the transmission path.
 5. The method according toclaim 1, wherein before transmitting the data packet addressinformation, the network transmission device checks whether identicaldata packet address information has already been sent to the resourcemanager, and the network transmission device transmits data packetaddress information only if identical data packet address informationhas not already been sent.
 6. The method according to claim 1, whereindepending on the data packet address information, the networktransmission device transmits routing information to the resourcemanager for recognizing connections running over the transmission path.7. The method according to claim 1, wherein transmission of the datapacket address information to the resource manager is dependent ontransmission information contained in the data packet, from which thedata packet address information was read.
 8. The method according toclaim 1, wherein the set of resources on the transmission path ismanaged by the resource manager according to at least one of serviceclass and priority class.
 9. The method according to claim 1, whereinthe network transmission device is controlled by the resource manager sothat together, the network transmission device and the resource managersafeguard performance of the connection.
 10. The method according toclaim 1, wherein a gatekeeper is provided for logical establishment ofthe connection.
 11. The method according to claim 2, wherein theconnection is established only if the resource request does not exceedavailable resources on the transmission path.
 12. The method accordingto claim 11, wherein the network transmission device transmits resourceinformation to the resource manager concerning available resources onthe transmission path.
 13. The method according to claim 12, whereinbefore transmitting the data packet address information, the networktransmission device checks whether identical data packet addressinformation has already been sent to the resource manager, and thenetwork transmission device transmits data packet address informationonly if identical data packet address information has not already beensent.
 14. The method according to claim 13, wherein depending on thedata packet address information, the network transmission devicetransmits routing information to the resource manager for recognizingconnections running over the transmission path.
 15. The method accordingto claim 14, wherein transmission of the data packet address informationto the resource manager is dependent on transmission informationcontained in the data packet, from which the data packet addressinformation was read.
 16. The method according to claim 15, wherein theset of resources on the transmission path is managed by the resourcemanager according to at least one of service class and priority class.17. The method according to claim 16, wherein the network transmissiondevice is controlled by the resource manager so that together, thenetwork transmission device and the resource manager safeguardperformance of the connection.
 18. The method according to claim 17,wherein a gatekeeper is provided for logical establishment of theconnection.
 19. A method for establishing a packet-orientedcommunication connections of predetermined performance, comprising:reading packet address information from data packets transmitted over atransmission path, the data packets being transmitted independently fromthe connection to be established, the address information identifyingthe origin and destination of the data packets and being read by arouter; transmitting the address information, along with informationidentifying the transmission path, from the router to a resourcemanager; transmitting a request to the resource manager in order toestablish the connection, the address information being transmittedbefore the request, the request having connection informationidentifying the origin and destination of the connection; using theconnection information and the address information to determine whetherthe origin and destination of the connection match the origin anddestination of the data packets; and if the origin and destination ofthe connection match the origin and destination of the data packets,then concluding that the transmission path is a possible route for theconnection such that a positive match causes further evaluation of thetransmission path.